ASDF makes available three functions to read system interdependencies. These are intended to aid programmers who wish to perform dependency analyses.
Returns a list of names of systems that are weakly depended on by system. Weakly depended on systems are optionally loaded only if ASDF can find them; failure to find such systems does not cause an error in loading.
Note that the return value for
system-weakly-depends-on is simpler
than the return values of the other two system dependency introspection